PROJECT SUMMARY Healthy sleep is important to behavioral, neurobiological, and physiologic health. Emerging literature suggests that stress biomarkers, such as cortisol, C-reactive protein (CRP), and body mass index (BMI) increase when healthy sleep habits are not regularly practiced among older children and adults. These biomarkers are associated with stress and increased risk for future disease. Researchers suggest that young children from racial/ethnic minority groups and/or living with socioeconomic adversity are especially vulnerable to poor sleep beginning within the first year of life. However, little is known about the relationships among sleep characteristics, stress, and health among very young children living with adversity. The proposed study will address this important scientific gap. This study will improve our understanding of these relationships during a critical developmental period in children's lives ? toddlerhood. Using a longitudinal design with repeated measures to prospectively examine the relationships among sleep characteristics, stress, and toddler's health from age 12 months to 24 months, we will address the following aims: 1. Examine changes in subjective and objective sleep characteristics from 12 to 24 months of age; 2. Examine changes in stress biomarkers from 12 to 24 months of age; 3. Examine the cross sectional and longitudinal relationships between sleep characteristics and stress response; 4. Examine the cross sectional and longitudinal relationships between sleep characteristics and toddlers' behavioral health. The sample will include 113 toddlers who live in socioeconomically disadvantaged homes. Data will be collected during at two time points (age 12 months and 24 months). Data on sleep characteristics will include subjective and objective measures of sleep duration and efficiency, obtained with questionnaires, diaries, and 9 days/nights of sleep actigraphy. Multi-systemic biomarkers of stress including cortisol, C-reactive protein, S-IgA, and BMI, will be measured individually and then explored as a latent variable of stress. Caregiver-reported behavioral health problems will be measured as it is closely associated with children's present and future health. Indicators of economic, environmental, and psychological adversity will be obtained and their relationships with primary variables will be explored. Generalized linear models will be used in the data analysis. Data from this study will be used to support future R-series grant applications designed to further understand the relationships among sleep, stress, and health by following these children over time with additional measures of stress and health to identify causal pathways and ultimately test the effects of interventions, such as those that may improve sleep, among young children at risk for toxic stress. While my past clinical and research experience focused on interventions to support parent- child relationships among families living with adversity, the next step in my career development is to acquire training to understand behavioral and biological aspects of sleep and stress and to explore the extent to which healthy sleep buffers toddlers' stress response to chronic stress early in life.